Question: Which of these numbers is composite? ${17,\ 29,\ 43,\ 61,\ 85}$
Answer: A composite number is a number that has more than two factors (including 1 and itself). 17, 29, 43, and 61 each have only two factors. The factors of 85 are 1, 5, 17, and 85. Thus, 85 is the composite number.